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Journal of Theoretical and Applied Information Technology 10 th June 2013. Vol. 52 No.1 © 2005 - 2013 JATIT & LLS. All rights reserved . ISSN: 1992-8645 www.jatit.org E-ISSN: 1817-3195 signal after the amplification. Base station combine the data from the user and its partners and make a decision. Although when the cooperation magnify the signal, the noise is also magnified, but the base station receive two independent declined signal, finally can make better decision. AF mechanism, which was developed by Laneman, was detailed analyzed13. The result shows that the diversity order of AF is two at high signal to noise power ratio region (SNR) under the conditions of two users. In AF, granted the Channel coefficient between user, we can get the optimum decoding, so AF must have necessary channel estimation and exchanges of information. It is not a simple technology for sample, amplification and retransmission of analog signal to AF. But overall, according to a simple cooperation mechanism that is easy for analyzing, it will be very helpful to further understand the later coordination communication system. CC was integrated the channel coding idea and coordination. CC send the different code word of each user by two independent fading channel. The basic idea is that each user send the redundant information increase to its partners. CC will return elastically to non- cooperation model when the channel between them is very poor. The outstanding characteristics of CC is to achieve coordination by designing channel coding Without the feedback between users. The source data sent from user includes value information and CRC information. Data sending cycle of each user is divided into two stages In CC. We call each stage for a frame. In first frame, the code word sent form user includes N 1 bits. Each user attempts to decode correctly on the data of partner. In second frame, if the decoding is correct, the user will calculate and send the second part of its partner, which includes N 1 bits. Otherwise, the user will send the second part of itself, which also includes N 1 bits. So the user send N = N1+ N2 bits in each cycle. Usually, all kinds of channel coding method can be used for coding cooperation network. For example the code words can be block code, convolution code or both of two. In Rate Compatible Punctured Convolution(RCPC)24, for example, the first frame can be obtained by hewing N 1 out of N , and the second frame is composed of bits that was poked. The monograph, which was published by Sendonaris, analysed the cooperation mechanism of DF under CDMA. In this mechanism, as a pair, two users support each other. Each user has its own spreading code C () t and C () 1 2 t . The data bits of two users are bi ( n ) , in which, i = 1, 2 is index number of user, n is expressed as time mark of information. Each signal cycle includes three bits space. X () t and X () 1 2 t are expressed as the signal of user 1 and user 2, respectively, so the signal is X () t = 1 (1) (2) (2) (2) ⎡a11b1 C1 (), t a12b ˆ 1 C1 (), t a13b1 C1 () t + a14b2 C2 () t ⎤ ⎣ ⎦ (1) X () t = 2 (1) (2) (2) (2) ⎡a21b2 C2 (), t a22b ˆ 2 C2 (), t a23b1 C1 () t + a24b2 C2 () t ⎤ ⎣ ⎦ (2) Each user sent itself bit information and detected the second bit of other users in the first and second interval. Two user sent the linear combination involving the second bit of itself and its partners in the third interval. To the first, second and third interval, the power was variable, According to the condition between uplink and user channel, the related transmission power is optimized, this method had self-adaptability for the state of channel. The power is allocated by a i, j , which the average transmit power is invariant. In short,, when the channel status was good, more power will be allocated for collaboration, otherwise the power will be decreased. 3. THE COOPERATIVE DIVERSITY MODEL OF MULTI-HOP RELAY WIRELESS SENSOR NETWORK Consider a multi-hop relay wireless sensor networks Ω ( N) , the number of node was N . S1 S2 S3 ... Sm R1 R2 R3 ... Rn Fig.2 Network Model Based On Cooperative Diversity 4
Journal of Theoretical and Applied Information Technology 10 th June 2013. Vol. 52 No.1 © 2005 - 2013 JATIT & LLS. All rights reserved . ISSN: 1992-8645 www.jatit.org E-ISSN: 1817-3195 As shown in Figure 2, the source (or relay) node sent the sign z i to the destination (or relay) node R j ( j = 1, 2,..., n ) at the rate of ù i , respectively z ,expressed as Si ⎯ ⎯→ i R j ,in which, i zÎ . To be more specific, the node S i 、 R ( i = 1,2,..., m, j = 1, 2,..., n) could be configured j for sending out complex value base-band signal flow a ik 和 b jk ( k = 1, 2,... N ), respectively , which were satisfied the conditions of node power in the average significance: N 1 2 ∑ | αik | „ PS ( i ) , N k = 1 (3) 1 N A i N 2 ∑ | β jk | „ PR ( j ) k = 1 When the source (or relay) node S i send the signal to the destination (or relay) node R j at the rate of p S i , the other destination (or relay) node Rw ( w≠ j) could listen and assist the distribution process by relay cooperation. Noted the signal received by the destination (or relay) node R ( j = 1, 2,..., n ) as ¡ ( ) , the channel was j rayleigh fading, noted the fading index as r ( j = 1, 2,..., n),noted Additive Gaussian White j Noise with zero mean and one variance as C ,which was the circle symmetrical IDD complex random variable. The channel gain between S i and R j was g ij , the cooperative diversity gain between R j and R w was G (cosθ jw + i sin θ jw) , in which, i was the unit of imaginary number, the range G was constant, the phase θ jw was the random variable distributed in [ − ππ , ] , thus, based on Si z ⎯ ⎯→ i R j R j , the model of receiving signal of source (or relay) node was ¡ ( R j ) = g ij z i + ∑ w G (cosθ + i sin θ ) z + C (4) w= 1,2, ... mw , ≠ j j = 1, 2,... n jw jw j j In which, z w j was sent by R w in z Si ⎯ ⎯→ i R j , C j was Additive Gaussian White Noise. The formula (4) could be noted as ¡ ( R , k) = g α + j ij ik ∑ G (cosθ + i sin θ ) β + C (5) w= 1,2, ..., nw , ≠ j j = 1,2,... n, k = 1, 2,... N jw jw wk jk The fading channel, which carried the information sent and receive by many sender and receiver, was a degenerate gaussian radio channel in this paper, in which, each sender and receiver had the different SNR that was depent on the state of the channel. In addition, unlike in the past, the transmitter sent many information flows with different rate and power, not sent simple information flow with constant rate and interrupt possibility. Then, many information flows were decoded when the condition of channel is poor, and more information could obtain more reliable decoding when the condition of channel is good. 4. CODING TECHNOLOGY AND DECODE RELAY Which way do Code Word transfer depent on receiving node. According to the information of receiving node, Code Word transferred many kind of information, supposed the sender node sent the information z kù 1 1 ∈{1, 2,..., 2 } z ∈ kù m {1,2,...,2 m } kù 2 , z2 ∈{1,2,...,2 } , …, (6) So the sender node would form a generalized information matrix, which was k 1 2 2 ù k k × 2 ù × × 2 ù m , matrix elements was random gaussian code, noted as X( ζ1, ζ2, ζm) . if channel capacity was C… ù 1+ ù 2 + + ù m , then the information z 1 , z 2 ,…, z m were decoded by the receiver node. If z ,..., i z 1 i , 1 „ i j 1 ,..., i j „ m,and C … z , then the receiver node decoded ∑ k≠i1, i2,..., i j k z k ( k ≠ i1 ,..., ij,1 „ k„ m) by the generalized information matrix. If the wireless channel, which the information was choose, according to a uniform probability by the information set in (6) and sent from the source (or relay) node to the destination (or relay) node, was point-to-point. For the wireless relay channel, Block Markov Coding was first developed by Madsen in the [3]. A signal, which would be sent, was divided into several blocks, each block of signal was encoded alone, supposed the signal z i 5
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